Effects of incorporating pyrite-analogous CoSe₂ on the thermoelectric properties of TiS₂

In this study, we delved into the thermoelectric characteristics of TiS₂ - x mol% CoSe₂ composites, with x varying from 0 to 3. The incorporation of a modest quantity of CoSe₂ prominently enhanced the grain orientation of TiS₂. Nevertheless, a subsequent increase in CoSe₂ content led to a rapid deterioration of the TiS₂ grain orientation. The electrical conductivity σ exhibited an initial surge followed by a decline upon the addition of CoSe₂. Conversely, the absolute Seebeck coefficient |S| initially decreased and then rose. Notably, the power factor PF of TiS₂ peaked at 14.4 μWcm⁻¹K⁻² upon the inclusion of 2 mol% CoSe₂, marking a substantial 1.7-fold enhancement compared to pristine TiS₂. Furthermore, the thermal conductivity κ of TiS₂ was effectively suppressed by the addition of CoSe₂. Consequently, TiS₂ - 2 mol% CoSe₂ achieved a ZT_max value of 0.59 at 673 K, representing a noteworthy 1.8-fold increase over pristine TiS₂.